Field of the Invention
The present invention relates to headlight devices.
Description of the Related Art
Headlights for vehicles have been known, which include a light deflector of a
MEMS (Micro Electro Mechanical Systems) and are configured to irradiate a region to be irradiated with reflected light from a mirror unit of the light deflector (e.g., JP 5577138 B).
A light deflector of a MEMS to be mounted on a headlight for vehicles typically includes a mirror unit that can reciprocally turn about first and second rotation axes that are orthogonal to each other, and an actuator configured to turn the mirror unit about the first and second rotation axes.
Let that the reciprocal turning of the mirror unit about the first and second rotation axes have a first frequency and a second frequency, respectively, one of these frequencies is set higher than the other, and the one frequency is set at the frequency of the natural oscillation of the mirror unit (resonant frequency) so as to allow the mirror unit to reciprocally turn stably at the high frequency.
In a conventional headlight device including a light deflector, the position of the region where emitted light scans is fixed relative to the vehicle. Therefore, when the vehicle travels along a curved road, for example, the irradiation region may be outside of the road, or a specific target may be outside of the irradiation region.
When the scanning region (irradiation region) of the scanning light is displaced horizontally, the direction of the light deflector as a whole is changed. To this end, the light deflector as a whole has to be turned by the actuator, which means a complicated structure of the light deflector. When the mirror unit is reciprocally turned at its resonant frequency, it is substantially difficult to adjust the center turning angle in the range of the reciprocal turning.